1. Field of the Invention
The present invention relates to a method and apparatus for transmitting data in a wireless communication system, and more particularly to a method and apparatus for transmitting uplink data in consideration of Mobile Station (MS) consumption power for enabling a UE to be stably operated at a cell edge.
2. Discussion of the Related Art
A wireless communication system has been widely used to provide various kinds of communication services such as voice or data services. Generally, a wireless communication system is a multiple access system that can communicate with multiple users by sharing available system resources (bandwidth, transmission (Tx) power, and the like).
A variety of multiple access systems can be used, for example, a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, a Single Carrier Frequency-Division Multiple Access (SC-FDMA) system, and the like.
It is necessary for the wireless communication system to control uplink transmission power, so that the magnitude of a reception (Rx) signal can be properly adjusted by a base station (BS). If transmission (Tx) power is two small in uplink (UL) transmission, the BS is unable to receive a transmission (Tx) signal from the UE. In contrast, if Tx power is too strong in UL transmission, a Tx signal of the UE may interfere with a Tx signal of another UE, resulting in an increase in battery power consumption. The magnitude of the Rx signal is kept in a proper level by controlling uplink transmission (UL TX) power, unnecessary power consumption is prevented from being generated in a UE, and a data transfer rate and the like are adaptively decided, resulting in an increase in transmission efficiency.
Therefore, it is necessary for various technologies for effectively controlling UL transmission power in a wireless communication system to be developed.
FIG. 1 is a graph illustrating a variation of power consumed by a Long Term Evolution (LTE) User Equipment (UE) which transmits data and/or control information via uplink. The UE transmits data and/or control information to a base station (BS) using transmission (Tx) power received from the BS according to an agreement between the UE and the BS. However, the BS may command the UE to transmit data and/or control information with a greater transmission (Tx) power in proportion to the increasing distance from the BS to the UE, so that total power consumption of the UE is increased in proportion to the increasing distance between the UE and the BS. However, the BS commands the UE to transmit data and/or control information with higher Tx power in proportion to a distance from the BS to the UE, so that total power consumption of the UE is increased in proportion to the distance from the UE to the BS.
FIG. 2 shows that UL data is transmitted with time in a cell edge region. Referring to FIG. 2, the UE is characterized in that it transmits data at all times so as to acquire a desired data throughput from a cell edge region having a poor environment.
The ‘Limitation of Power Consumption’ line shown in FIG. 1 indicates maximum power amount capable of being normally supplied from a primary power-supply unit, and represents a reference line at which the UE is turned off or does not perform the corresponding faulty operation. For example, assuming that the primary power-supply unit provides power higher than the ‘limitation of power consumption’ line to the UE, the UE may be excessively heated or the power of the primary power-supply unit is consumed in a short period of time.
In accordance with the related art, if total power consumption of the UE is higher than the ‘limitation of power consumption’ line, it is impossible to guarantee a service of a predetermined level. In particular, power consumption of the UE is higher than the ‘limitation of power consumption’ line in a cell edge region distant from the BS, and the UE transmits UL data at almost all times, so that a faulty operation occurs due to a shortage of UE power and it may be impossible to provide a service to the UE or a user.
As described above, according to the related art, if total power consumption of the UE is higher than the ‘limitation of power consumption’ line, a faulty operation occurs in the UE.